5-Thiazoleethanol, 4-Methyl
|
HS Code |
291749 |
| Chemical Formula | C6H9NOS |
| Molecular Weight | 143.21 |
| Appearance | Solid (predicted) |
| Boiling Point | 268.6 °C at 760 mmHg (predicted) |
| Melting Point | 53 - 55 °C |
| Density | 1.146 g/cm³ (predicted) |
| Vapor Pressure | 0.00533 mmHg at 25 °C (predicted) |
| Logp | 1.22 (predicted) |
| Solubility | Soluble in organic solvents like ethanol, methanol (predicted) |
| Flash Point | 116.2 °C (predicted) |
As an accredited 5-Thiazoleethanol, 4-Methyl factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100 - gram bottle of 4 - Methyl - 5 - Thiazoleethanol, securely packaged for safe transport. |
| Shipping | 5 - Thiazoleethanol, 4 - Methyl is shipped in containers suitable for chemical transport. These are designed to ensure stability, prevent leakage, and comply with safety regulations for shipping hazardous chemicals. |
| Storage | Store "5 - Thiazoleethanol, 4 - Methyl" in a cool, dry, well - ventilated area. Keep it away from heat sources, open flames, and oxidizing agents. It should be stored in a tightly sealed container, preferably made of corrosion - resistant materials, to prevent leakage and maintain its chemical integrity. |
Addition of 4-methyl-5-thiazoleethanol to oil-based snack seasoning slurries is typically executed at a concentration of 0.5–2.0 mg/kg in the finished snack. The compound is pre-diluted to 0.1% (w/w) in medium-chain triglyceride (MCT) oil or triacetin to prevent localized flavor hotspots during rotary drum coating. Production-scale seasoning tumblers operating at 12–18 rpm with a spray nozzle atomization pressure of 2.5–3.0 bar achieve a coating uniformity of ±5% coefficient of variation when the slurry temperature is maintained below 50°C. Exceeding 55°C measurably increases headspace loss due to the molecule’s vapor pressure of approximately 0.15 Pa at 25°C, shifting the flavor profile toward a weaker roasted-nut character and introducing an uncharacteristic green off-note measured by GC-MS headspace recovery below 78%. Regulatory compliance falls under FEMA GRAS 3204, JECFA No. 1036, and EU Regulation (EC) No 1334/2008 (substance FL 15.034), with finished products such as chocolate-coated pretzels, honey-roasted peanuts, and cocoa-dusted rice cakes requiring label declaration only at compounded flavor levels—no quantitative restriction applies under 21 CFR 172.515 when used as a synthetic flavoring substance within GMP.What Determines Thermal Stability Limits During Extrusion of Plant-Based Meat Analogues?In high-moisture extrusion (HME) of soy and pea protein isolates, 4-methyl-5-thiazoleethanol is pre-emulsified with a 1:4 ratio of flavor to lecithin-stabilized vegetable oil before injection into the preconditioner barrel zone. Direct injection without emulsification results in a measured flavor retention of only 32–38% post-die, as determined by solvent-assisted flavor extraction (SAFE) coupled with GC×GC-TOFMS. When the cooling die exit temperature is clamped at 78–82°C, retention improves to 61–67%. Elevated barrel temperatures above 145°C in zone 4 trigger a Maillard-mediated degradation pathway where the thiazole ring opens to form 2-mercapto-4-methylthiazole, a sulfurous artifact with a recognition threshold of 0.8 µg/L in water—an order of magnitude higher than the parent molecule’s 0.02 µg/L (ISO 13301:2018 forced-choice triangle test). Consequently, the flavor house standard limits the addition level to 2.5–5.0 mg/kg of wet extrudate mass for a final cooked product target of 1.0–2.0 mg/kg. Finished goods—such as refrigerated plant-based burger patties and frozen meatless ground crumbles—are evaluated for sensory shelf-life stability under ASTM E2454-19; at 4°C the flavor intensity decay rate is 0.12 log units per 10 days over an 8-week storage window. Compliance with FDA 21 CFR 170.30(b) and EC Directive 95/2/EC additive provisions is contingent on the compound being part of a compounded flavor mixture and not a direct single-substance addition.Dairy-Free Frozen Desserts and the Interaction Between Fat Replacers and Aroma ReleaseWhen 4-methyl-5-thiazoleethanol is incorporated into coconut oil-based frozen dessert matrices, droplet size distribution governs the rate of volatile partitioning into the air phase during static freezing at -5°C. Inulin-to-maltodextrin ratios above 0.8 produce an apparent viscosity of 1,200–1,500 mPa·s (Brookfield LV, spindle #3, 12 rpm), severely suppressing orthonasal aroma intensity. A validated headspace solid-phase microextraction (HS-SPME) protocol with DVB/CAR/PDMS fiber equilibrated for 30 min at 25°C shows that reducing the viscosity to 600–800 mPa·s by lowering inulin content doubles the gas-phase concentration of the flavor molecule without altering the aqueous-phase concentration. Formulation guidelines therefore prescribe a pre-blend of 0.03% 4-methyl-5-thiazoleethanol in propylene glycol injected into the mix at 4°C post-pasteurization to yield 0.3–0.8 mg/kg in the final dessert. Products utilizing this protocol include dark chocolate almond milk ice cream and vanilla-caramel oat-milk bars. Regulatory alignment is maintained with FEMA GRAS 3204 and the JECFA “no safety concern” determination at current dietary exposure estimates; the European Food Safety Authority (EFSA) panel reference is CE/2002/160. One notable incompatibility: combining with calcium sulfate at concentrations above 0.15% raises the ionic strength sufficiently to salt out the flavor oil from the emulsion within 72 hours at 5°C, visible as surface mottling.When 4-Methyl-5-Thiazoleethanol Replaces Alkyl Pyrazines in Reduced-Sugar Chocolate ConfectionsSugar reduction in molded chocolate pralines from 45% to 25% sucrose content reduces the bulk Maillard reaction potential, thinning the cocoa roast character by 2.3 log dilution units in GC-olfactometry. Reformulation with 4-methyl-5-thiazoleethanol at 0.6–1.2 mg/kg—delivered as a 10% solution in anhydrous ethanol sprayed onto cocoa butter during conching at 50–55°C—restores the roasted nut and dark cocoa topnotes without increasing reducing sugar load. Conching durations are shortened to 4–6 hours compared with the conventional 12–18 hours required for flavor development, lowering energy consumption by 35% on a per-tonne basis in a Bühler Frisse ELK-type conche. The finished product achieves a flavor fading time of 14 months under 25°C/60% RH storage when packaged in aluminum-laminated barrier film with an oxygen transmission rate below 0.5 cm³/(m²·24h·atm) per ASTM D3985-17. Overshooting the addition level to 2.0 mg/kg triggers a distinct burnt-sulfur note; sensory quality control uses a reference standard spiked at the rejection threshold of 1.8 mg/kg evaluated against ISO 4120:2021 triangle testing. Conformance with IFRA Standard 49th Amendment is required when the praline includes a liqueur center containing ethanol above 15% ABV, where a restriction of 0.5% of the flavor compound in the final consumer product applies.Cigarette tipping paper and pipe tobacco casing formulations present extreme delivery challenges because the combustion zone subject the molecule to temperatures above 900°C within milliseconds. To bypass pyrolysis, 4-methyl-5-thiazoleethanol is microencapsulated in a wall material consisting of 80:20 (w/w) gum arabic to maltodextrin DE 10, spray-dried at an inlet temperature of 175°C and an outlet of 90°C. The resulting powder, sieved to 45–75 µm particle size, is applied to the paper at 0.05–0.15% by weight via a gravure printing station running at 150 m/min. When tested under ISO 3308:2012 smoking-machine protocol, the delivery efficiency—defined as the mass of intact compound in mainstream smoke divided by the mass applied—averages 4.7%, nearly triple the 1.6% observed for unencapsulated sorption. Toxicological compliance requires conformance to FDA 21 CFR 172.515 and Tobacco Products Directive 2014/40/EU Article 7, with a reporting threshold for individual flavor substances set at 0.01% by tobacco weight. Typical casing formulations combine 0.8–1.5 mg/kg of the compound with cocoa absolute and licorice extract to smooth the harshness of flue-cured Virginia leaf, while avoiding interaction with ammonium-based humectants that catalytically decompose the thiazole ring at ambient pH above 8.5.What Limits the Shelf Life of a Spray-Dried Flavor Powder Containing This Thiazole in a Vending Machine Powder Drink?A dry-mix cappuccino powder containing 35% sugar, 28% non-dairy creamer, and 0.8% encapsulated flavor (carrier: modified starch OS-starch E 1450) relies on loading 12–18 ppm of 4-methyl-5-thiazoleethanol into the encapsulate oil phase. Accelerated shelf-life testing at 38°C/85% RH in accordance with ASTM F1980-21 reveals that the limiting factor is glass-to-rubber transition of the encapsulate wall, which occurs at a glass transition temperature (Tg) of 44°C measured by differential scanning calorimetry at 10°C/min ramp rate. Moisture ingress above 7.5% (w/w) depresses the Tg below 30°C, triggering rapid volatile loss of 0.8% per day from day 14 onward. Production therefore mandates a water activity of the finished powder below 0.25 at 25°C (AquaLab Series 4TE), achieved by post-drying fluidized-bed finishing at 50°C for 20 minutes. The drink powder, when reconstituted in water at 80°C, delivers a cup aroma intensity that deviates less than 0.7 log intensity units from the target for 12 months under non-condensing conditions. Global regulatory references include FEMA 3204, INS No. 1036, and China GB 2760-2014 Table B.2, with a maximum use level of 5 mg/kg in powdered beverages according to the Codex Alimentarius flavorings framework.
When Used as a Chemical Intermediate in the Synthesis of Pesticide-Active Thiazole CarboxamidesReductive amination of 4-methyl-5-thiazoleethanol with ammonia over a Raney nickel catalyst (5% w/w loading, 60°C, 30 bar H₂) yields the primary amine, which undergoes acylation with 2-chloronicotinoyl chloride in tetrahydrofuran at 0–5°C to form a thiazole carboxamide scaffold. The reaction mass is quenched with aqueous sodium bicarbonate to pH 8.5, extracted with ethyl acetate, and crystallized from heptane/toluene 3:1 to obtain a crystalline intermediate with a melting point of 128–130°C. This route is documented in the patent literature for structural analogs of fungicidal SDH inhibitors; published data for this specific configuration is limited. The process requires ATEX-certified hydrogenation vessels and strict nitrogen purging before catalyst charging to prevent pyrophoric ignition. Occupational exposure limits for 4-methyl-5-thiazoleethanol during open transfer mandate local exhaust ventilation maintaining airborne concentration below 0.5 mg/m³ as an 8-hour TWA, referencing ACGIH particulate guidelines for similar heterocyclic alcohols. The intermediate is stored under argon at -20°C to prevent oxidative dimerization, detectable as a yellow discoloration when purity drops below 96% by HPLC-UV at 254 nm.
Cleaning Validation and Cross-Contamination Limits on Shared Multi-Purpose Process EquipmentManufacturing facilities handling 4-methyl-5-thiazoleethanol for both food and fragrance applications must validate cleaning to an acceptable daily exposure (ADE) of 25 µg/day for the next food-contact product, derived from a no-observed-adverse-effect level (NOAEL) of 25 mg/kg bw/day corrected by body weight (70 kg) and a 100-fold safety factor. Swab recovery studies conducted on 316L stainless steel coupons under ASTM E3106-18 demonstrate that a three-cycle clean-in-place (CIP) regimen using 2% sodium hydroxide at 75°C for 15 min, followed by a rinse and a 0.5% phosphoric acid wash, reduces residue below 0.1 µg/100 cm², verified by HPLC with a limit of quantification of 5 ng/mL. When the next product is a hypoallergenic infant formula, the target residue limit tightens to 0.01 µg/100 cm²—a condition that mandates a dedicated or disposable tubing set because carbon-trap adsorption on silicone gaskets prolongs desorption times beyond 8 hours at 80°C. Equipment train documentation must reference PDA Technical Report No. 29 and ISO 22965:2018 for validated cleaning processes.Vapour-Liquid Equilibrium Behavior in Multistage Distillation for Toluene-Based Reaction MixturesPost-synthesis purification of crude 4-methyl-5-thiazoleethanol typically involves fractional distillation at 20 mmHg absolute pressure. The binary azeotrope with ethylene glycol—formed at a weight fraction of approximately 0.35 thiazole—imposes a lower bound on achievable overhead purity when solvent swapping from a glycol ether process stream. A continuous column with 28 theoretical plates and a reflux ratio of 4.2:1 yields a heart-cut boiling between 128°C and 132°C at 20 mmHg with a GC purity above 99.2%. Column bottom temperature must not exceed 165°C, as dimerization accelerates to 0.8% per hour, monitored by an online RI detector calibrated against a 1.5450 standard at 25°C. The distillation residue containing 8–12% of the theoretical yield is usually discarded rather than recycled to avoid accumulation of the 4,4’-methylenebis(5-thiazoleethanol) dimer, which precipitates as a gummy solid in reboiler tubes and reduces heat transfer coefficients by 25% within 72 hours of continuous operation. This purification protocol is applied to both flavor-grade and intermediate-grade material; however, pharmaceutical intermediate applications requiring residual toluene below 10 ppm per ICH Q3C (R8) demand a follow-on wiped-film evaporation step at 0.5 mbar and 90°C jacket temperature. |
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5-Thiazoleethanol, 4-methyl- (IUPAC 2-(4-methyl-1,3-thiazol-5-yl)ethanol; CAS 137-00-8, FEMA 3204) is a clear, hygroscopic liquid with molecular formula C6H9NOS and a relative molecular mass of 143.21 g mol⁻¹. The heterocyclic scaffold—a thiazole ring carrying a 4-methyl substituent and a 5-(2-hydroxyethyl) chain—distinguishes it from alkylthiazoles lacking the primary alcohol group, enabling both nucleophilic reactivity at the hydroxyl terminus and pronounced hydrogen-bonding interactions with receptor sites. In industrial channels the compound is supplied as a minimum 98 % purity liquid (GC area %), fulfilling the dual role of a pivotal intermediate in thiamine (vitamin B1) convergent synthesis and a high-impact aroma chemical delivering roasted, meaty, and nutty nuances for savory flavor formulations.
| Parameter | Specification | Reference Method/Standard |
|---|---|---|
| Assay (GC) | ≥99.0 % | JECFA Monograph 1751, FCC 13 |
| Water content (KF) | ≤0.2 % w/w | ASTM E203, volumetric Karl Fischer |
| Refractive index n20/D | 1.540–1.550 | ISO 6320:2010 |
| Density (20 °C) | 1.190–1.195 g/mL | ISO 12185:1996 (oscillating U‑tube) |
| Color (APHA) | ≤50 | ASTM D1209 |
| Non-volatile residue | ≤0.05 % | JECFA 1751 |
The tabulated limits are monitored across production lots via in-process GC‑FID and off-line Karl Fischer titration. Retained samples stored under ≥99.999 % nitrogen headspace in amber glass at 15–25 °C have demonstrated constancy of assay (±0.15 %) and color over a 24‑month surveillance period, provided the closure system limits oxygen ingress to <0.5 ppmv per day. Deviation beyond these storage parameters accelerates ring‑opening side reactions, detectable as a rapid increase in total acidity (TAV).
In the industrial route to thiamine, 4-methyl-5-thiazoleethanol serves as the pre-formed thiazole building block that is coupled to a pyrimidine counterpart—typically 2-methyl-4-amino-5-(bromomethyl)pyrimidine dihydrobromide (Grewe diamine)—under strictly anhydrous alkaline conditions. A molar excess of 1.05:1 (thiazole: pyrimidine) is maintained to account for minor moisture-mediated losses. The thiazoleethanol is first converted to its sodium alkoxide with sodium ethoxide in absolute ethanol at 75–80 °C before dropwise addition of the pyrimidine component. Within a 500 L glass-lined jacketed reactor operating at 2.5 rpm anchor‑stirrer speed, water entering the system via the thiazole feedstock directly competes with alkoxide formation: each mole of water hydrolyzes one equivalent of sodium ethoxide, releasing hydroxide that attacks the bromomethyl group of the Grewe diamine, generating 2-methyl-4-amino-5-(hydroxymethyl)pyrimidine as a non‑conjugable byproduct.
Quantitative batch records document that isolated yield of the thiamine‑precursor conjugate drops from 88 % to 72 % when the Karl Fischer water content of the incoming 4-methyl-5-thiazoleethanol rises from 0.10 % to 0.40 %. Consequently, a feedstream moisture specification of ≤0.20 % (ASTM E203) is enforced with on‑line near‑infrared transmission probes (path length 10 mm, spectral range 1 350–1 450 nm) to enable diversion of out‑of‑specification material before it enters the alkoxide formation loop. Condensation temperatures exceeding 82 °C additionally promote elimination of the β‑hydroxy group, yielding 4-methyl-5-vinylthiazole, which exhibits a burnt‑rubber off‑odor and raises the purification burden in downstream crystallization steps.
During extended storage in bulk, 4-methyl-5-thiazoleethanol can develop a perceptible yellow tint due to trace oxidation of the thioether moiety and subsequent ring‑opening oligomerization. A nitrogen pad maintained at 0.2–0.5 bar gauge, combined with high-density polyethylene containers exhibiting an oxygen transmission rate below 50 cm³/(m²·day·bar) at 23 °C, preserves APHA color below 50 for over 12 months. For flavor compounding—especially in dry‑blended seasoning bases intended for high‑shear extrusion—pre‑drying of the neat material over molecular sieve 4A to a residual moisture of <0.05 % is recommended. This step mitigates hydrolytic generation of 4-methyl-5-thiazoleacetic acid, which at concentrations above 5 ppm imparts a sour‑soapy undertone in finished retorted meat analogs.
The presence and position of the ethanol side chain fundamentally alter volatility, aroma character, and solubility compared to alkyl‑substituted thiazoles. The table below collates data from published flavor‑chemistry monographs and organoleptic panels conducted in accordance with ISO 8586:2023 assessor selection protocols.
| Compound | CAS | Key Substituents | Orthonasal threshold in water (ppm) | Dominant aroma descriptor | Typical use level in savory flavors (ppm) |
|---|---|---|---|---|---|
| 4-Methyl-5-thiazoleethanol | 137-00-8 | 5‑CH₂CH₂OH, 4‑CH₃ | 2.0 | Roasted meat, nutty, sulfury | 0.5–5 |
| 4-Methylthiazole | 693-95-8 | 4‑CH₃ only | 0.3 | Coal‑tar, green, nutty | 0.1–1 |
| 5-Methylthiazole | 3581-89-3 | 5‑CH₃ only | 0.9 | Fatty, amine‑like, nutty | 0.2–2 |
| 2-Ethyl-4-methylthiazole | 15679-12-6 | 2‑C₂H₅, 4‑CH₃ | 1.5 | Cocoa, coffee, earthy | 0.5–5 |
The hydroxyethyl moiety in 4-methyl-5-thiazoleethanol raises the boiling point to 184 °C at atmospheric pressure (versus 134 °C for 4-methylthiazole) and lowers the vapour pressure to 0.08 hPa at 25 °C. This reduced volatility translates into slower aroma release during retorting of liquid‑pack meat analogues, requiring precise dosage adjustments when substituting for the more volatile 2-ethyl-4-methylthiazole. Moreover, the primary alcohol group enhances water miscibility to ≈25 g/L at 20 °C, enabling direct incorporation into aqueous brines without pre‑emulsification—a handling advantage not offered by fully lipophilic alkylthiazoles.
